At least 35 manatees died from the cold between Jan. 1 and 26, compared with seven over the same period last year, according to the Florida Fish and Wildlife Conservation Commission.

An average of eight manatees died from the cold in the month of January from 2013 to 2017.

Manatees are ill-adapted to survive in frigid water. Their bodies are mostly lungs and ribs — they have deceptively little blubber.

The last time Florida saw an uptick in cold-related manatee deaths was in 2010 and 2011 when the number of manatees that died from the cold reached 282 and 114, respectively.

"It's been really busy," said Maya Rodriguez, a veterinarian at Miami Seaquarium, which rehabilitates sick manatees.

Manatees can develop hypothermia, or cold shock, when exposed to very cold water. A manatee suffering from cold shock will die quickly.

Prolonged exposure to water below 68 degrees can cause a condition called chronic cold-stress syndrome. The animal may suffer from emaciation, dehydration, skin lesions and infections. If found in time, these manatees have a chance at being rescued.

Most of the cold-related manatee deaths in Florida occurred between Jan. 15 and 22 as nighttime air temperatures dipped into the 30s. At least 19 manatees died from the cold during that period, state figures show.

Most of those deaths were caused by cold shock; the manatees were already dead when they were found.

"It was really sad; we didn't even get a chance to help them," Rodriguez said.

Those found alive in cold water are very weak and often suffer from "flipper frost," Rodriguez said.

The manatees are placed in warm water and are fitted with life jackets to help support their heads. Then they're put on antibiotics and are tube-fed high-nutrient food.

In Collier County at least one manatee died from the cold in January. The manatee was found in Marco Island. Another two manatees were too decomposed when found to determine the cause of death, state figures show.

On Monday at Port of the Islands in southern Collier County, officials found another two manatees that were described as "emaciated" and in "critical condition." They were taken to the Miami Seaquarium. One died in transport; the cause of death has not been determined.

Lee County also saw at least one cold-related death in January. That manatee was found in the Caloosahatchee River in Fort Myers. Three others were found but were too decomposed to determine the cause of death, state figures show.

Brevard County saw the most deaths caused by cold temperatures in January. There, state figures show, six manatees died from exposure to the cold.

When the temperatures drop, manatees seek warmer water in or near springs and around power plants. Oftentimes these areas do not have seagrass, which manatees eat, and the animals must venture into colder waters to feed, running the risk of dying from the cold.

When the weather is cold and sunny, manatees spend more time at the surface to warm up, increasing their risk of being hit by a boat.

"It's a major concern," said Pat Rose, executive director of the Save the Manatee Club. "What's most important is that people stay on the lookout for manatees."

Manatee deaths from watercraft injuries have increased in recent years to more than 100 in 2016 and 2017; however the overall population has rebounded since the early 1990s when numbers were below 1,500.